Hello, 

Don't worry first you applied the improvement exam in physics theory and next  do your hard work and also prepared important notes then you get the good score. After that you applied  the b.tech.

All the best. 

You should apply for improvement exam only in physics theory in which you are not passed.and work hard to get good marks next time because you get only one chance to attempt the improvement exam .after that you can do b.tech.